DPPF ligand imines

The N-aryl imines 412 as protected anilines can be prepared by Pd-catalysed arylation of benzophenone imine with aryl halides using DPPF and BINAP as ligands, and aniline derivatives are obtained by deprotection [204a],... 

Presumably, the use of a bidentate ligand such as ( )-BINAP or DPPF results in the occupation of a vacant coordination site, preventing -hydride elimination of the Pd (II) amide intermediate [53]. Dissociation of the imine and C-H bond reductive elimination results in formation of the reduced aryl bromide. If this -hydride elimination is rapid relative to reductive elimination and reversible, then significant erosion of the enantiomeric excess of optically active a-substituted amines maybe observed during the reaction (Scheme 3). 

Benzophenone imine was used extensively as an ammonia equivalent by various research groups [49,174], mostly with BINAP or dppf as ligands [2]. Diallylamine... 

More recently, Morris reported the hydrogenation of benzonitrile catalyzed by a ruthenium complex containing a P-NH-NH-P tetradentate ligand (Equation 15.121). The presence of an amine N-H and metal hydride make it likely that the reaction occurs by an outer-sphere mechanism involving two sequential simultaneous transfers of the hydride and the N-H proton, first to the nitrile and second to the imine (Scheme 15.27). This proposal was supported by DPT calculations. The hydrogenation of aryl and heteroaryl nitriles catalyzed by a combination of [Ru(COD)(2-methylallyl) J and DPPF has also been reported to occur in high yields. 

A number of other protocols for the application of benzophenone imine as ammonia surrogate have been reported using DPEPhos (12) [61], BINAP (1) [62,63], or DPPF (9) [64] as ligands. DPPF was used on a 5.3kg scale by Merck for the synthesis of a 2-aminopyridine derivative, rendering the potential for the synthesis of substituted heterocycles (Scheme 13.10) [64]. 

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